A service pack (SP), a term used by IBM and Microsoft, is basically a collection of updates, bug fixes and improvements. The latest service pack for Windows XP is SP. You can update to SP2 here: Service pack 2 for Windows XP.

Finding out which Service Pack you have is very easy.Press the Windows key and Pause|Break at the same time and look in the System part of the System Properties Window.

Updating to Service Pack 2 has many advantages: several fixed security issues, better operation and various bug fixes.